1. Technical Field
The present invention generally relates to a gas operating system for firearms that allows firing of different cartridge loads for a given shell caliber or gauge.
2. Related Art
Automatic and semiautomatic shotguns having user-adjustable gas systems are known. Adjustable gas systems allow a user to control the amount of gas entering into and/or vented from the system, which allows a wider range of cartridge loads to be fired from a single firearm. However, if an adjustable gas system is set for heavy loads and the weapon is used to fire light loads, the firearm may not fully cycle, which may require the user to manually cycle the bolt in order to load the next round. If the adjustable gas system is set for light loads and the weapon is used to fire a heavy load, the bolt velocity after firing may result in improper cycling and the weapon may suffer reduced part life for certain components.
Firearms such as the Remington M/1187 have self-compensating gas systems. Self-compensating gas systems allow a wider range of loads to be fired without requiring adjustment of the gas system. However, the wide range of available cartridge loads may not be sufficiently compensated by conventional self-compensating systems. For example, 12 gauge loads have a wide spread from light 2¾″ loads to heavy 3½″ loads. As a result, some self-compensating designs may not reliably operate light loads under all conditions, and may suffer undesirably high bolt velocities when firing heavy magnum loads.